Tanaka T, Saiki O, Doi S, Negoro S, Kishimoto S
Third Department of Internal Medicine, Osaka University, Japan.
J Immunol. 1988 Jan 15;140(2):470-3.
In this report, we examined whether novel interleukin 2 (IL-2) binding molecules (p70/75) are responsible for signal transduction and internalization of IL-2 in T cells by using a monoclonal antibody H-31 to Tac antigens. We found that H-31 inhibited the binding of IL-2 to Tac antigens but not novel IL-2 binding molecules. Scatchard plot analysis revealed that in the presence of H-31, intermediate affinity sites (Kd = 1 to 1.5 nM) were detectable and the number of them was similar to that of high affinity IL-2 receptor (IL-2R) (Kd = 10 to 15 pM) in the absence of H-31. Furthermore, the kinetics of endocytosis of IL-2 via p70/75 showed the same pattern as via high affinity IL-2R. Finally, high doses of IL-2 (100 to 10,000 U/ml) are required for the proliferation of T cells in the presence of H-31, whereas in the absence of H-31, physiologic doses of IL-2 (1 to 100 U/ml) induced the proliferation. These results taken together suggest that novel IL-2 binding molecules are related to signal transduction of IL-2 and that Tac antigens are essential for constructing of high affinity IL-2R, although Tac antigens may not be responsible for signal transduction.
在本报告中，我们使用抗Tac抗原的单克隆抗体H-31，研究了新型白细胞介素2（IL-2）结合分子（p70/75）是否负责IL-2在T细胞中的信号转导和内化。我们发现H-31抑制IL-2与Tac抗原的结合，但不抑制新型IL-2结合分子。Scatchard作图分析显示，在存在H-31的情况下，可检测到中等亲和力位点（Kd = 1至1.5 nM），其数量与不存在H-31时高亲和力IL-2受体（IL-2R）（Kd = 10至15 pM）的数量相似。此外，IL-2通过p70/75的内吞动力学与通过高亲和力IL-2R的内吞动力学表现出相同的模式。最后，在存在H-31的情况下，T细胞增殖需要高剂量的IL-2（100至10,000 U/ml），而在不存在H-31的情况下，生理剂量的IL-2（1至100 U/ml）即可诱导增殖。综合这些结果表明，新型IL-2结合分子与IL-2的信号转导有关，并且Tac抗原对于高亲和力IL-2R的构建至关重要，尽管Tac抗原可能不负责信号转导。
